Aged Control Rats Research Articles

Amla (Emblica officinalisGaertn.) prevents dyslipidaemia and oxidative stress in the ageing process

Amla (Emblica officinalis Gaertn.) is widely used in Indian medicine for the treatment of various diseases. We have investigated the effects of amla on the lipid metabolism and protein expression involved in oxidative stress during the ageing process. SunAmla or ethyl acetate extract of amla, a polyphenol-rich fraction, was administered at a dose of 40 or 10 mg/kg body weight per d for 100 d to young rats aged 2 months and aged rats aged 10 months. The lipid levels, such as cholesterol and TAG, in serum and liver were markedly elevated in aged control rats, while they were significantly decreased by the administration of amla. The PPARalpha is known to regulate the transcription of genes involved in lipid and cholesterol metabolism. The PPARalpha protein level in liver was reduced in aged control rats. However, the oral administration of amla significantly increased the hepatic PPARalpha protein level. In addition, oral administration of amla significantly inhibited the serum and hepatic mitochondrial thiobarbituric acid-reactive substance levels in aged rats. Moreover, the elevated expression level of bax was significantly decreased after the oral administration of amla, while the level of bcl-2 led to a significant increase. Furthermore, the expressions of hepatic NF-kappaB, inducible NO synthase (iNOS), and cyclo-oxygenase-2 (COX-2) protein levels were also increased with ageing. However, amla extract reduced the iNOS and COX-2 expression levels by inhibiting NF-kappaB activation in aged rats. These results indicate that amla may prevent age-related hyperlipidaemia through attenuating oxidative stress in the ageing process.

Potentiation of erythroid abnormalities following macrophage depletion in aged rats

The effects of prolonged macrophage depletion on haematological parameters were investigated in aged rats and compared with those in young ones. Four weekly i.v. injections of dichloromethylene diphosphonate-containing liposomes (Cl2MDP-CL) were employed to achieve a prolonged depletion of bone marrow (BM) and spleen macrophages. The number of BM macrophages was then assessed by flow cytometry, whereas the spleen clearance function was judged by the elimination of oxidised red blood cells (RBC). Haematological parameters and signs of RBC ageing (reduced MCV, increased density and augmented 4.1a/4.1b membrane protein ratio) were determined. Finally, the recovery from phlebotomy-induced acute anaemia was investigated. Following the Cl2MDP-CL treatment, in comparison with young rats, the aged animals showed: (i) reduced numbers of BM macrophages; (ii) greater impairment of spleen clearance function; (iii) similar anaemic condition and signs of RBC ageing; (iv) greater increase in white blood cell (WBC) numbers (mainly neutrophils). In addition, whereas aged control rats showed a recovery from phlebotomy-induced acute anaemia which was similar to that of the untreated young animals, in the aged-treated rats, a significantly diminished/delayed restoration of RBC, Hb and reticulocyte to normal values was observed, accompanied by a significantly higher increase in WBC numbers than in the other groups of animals. Haematological abnormalities because of Cl2MDP-CL-induced macrophage depletion are potentiated in aged rats in which the BM regenerative potential of the erythroid lineage as well as the clearance function of the spleen appear compromised. Thus, in aged rats, macrophage dysfunction is likely to interfere with erythroid homeostasis particularly during haemopoietic stress.

Effect of Streptozotocin‐Induced Type 1 Diabetes Mellitus on Contraction, Calcium Transient, and Cation Contents in the Isolated Rat Heart

Cations play major physiological and biochemical roles in the excitation-contraction coupling processes in the heart. This study investigated the effect of streptozotocin (STZ)-induced type I diabetes mellitus (DM) on contraction, calcium transient [Ca2+]i, and cation contents in the isolated rat heart compared to age-matched control. Diabetes rats weighed significantly (P < 0.05) less compared to control. They also had significantly (P < 0.05) elevated blood glucose compared to control. The whole heart, as well as the atria, right and left ventricles of the diabetic heart weighed significantly (P < 0.05) less compared to hearts from age control rats. The force of contraction and time to peak (t-pk) contraction in diabetic ventricular myocytes increased significantly (P < 0.05) compared to control. By contrast, these parameters did not change for the Ca2+ transient except for the time to half (t(1/2)) relaxation. The levels of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), iron (Fe2+), copper (Cu2+), and zinc (Zn2+) in the hearts varied from diabetic compared to control animals. The results indicate that 6-8 weeks of STZ-induced DM is associated with marked changes in contraction and in cation contents of the heart. The delay in the t(1/2) relaxation of the Ca2+ transient may be responsible for the elevated contraction seen in the diabetic heart. Moreover, the changes in cation contents in the heart may be responsible for abnormal cardiac rhythms and activity during DM.

A Decrease in FasL‐mediated apoptosis in the aging rat foot

Decubitus ulcers detract from the quality of life in many aging, debilitated individuals. Although load, shear stress and ischemia are important physical factors in decubitus ulcer formation, no clear mechanisms of ulcer creation have been reported. A recent review (Immunol. Rev. 205:June 2005) suggested that age-related apoptosis impairment occurs. To evaluate apoptosis in decubitus ulcer formation and under AAALAC approved rules, we utilized a population of aging SD rats that occasionally developed spontaneous ulceration on weight-bearing footpads. Apoptosis was evaluated by Fas ligand (FasL) stain of footpads of aging and young control rats. Sections of healthy young (10 weeks) and healthy aging (2.5 year-old rats) footpads were harvested at necropsy, paraffin embedded, sectioned, and stained with H&E or anti-rat FasL. Sites of decubitus ulcers were also evaluated with guidance of a pathologist. Density of FasL staining for each epidermal layer (stratum corneum, granulosum, spinosum, and basale) was scored from a computer-based template and the density scores subjected to analysis (Statistica database). FasL staining was significantly elevated in the stratum granulosum of young rat feet compared to old rat feet, p=0.02. In the granulosum the cells are dying to produce the cornified external layer that preserves skin integrity. The lowered FasL staining in the granulosum suggests that in this model an age-related impairment exists in FasL mediated apoptosis. The understanding of decubitus ulcers at the cellular level can assist in prevention and contribute to improved and more mechanism-specific treatment. Funding: Internal, UMKC School of Medicine

Modulatory role of grape seed extract on age-related oxidative DNA damage in central nervous system of rats

Aging is the accumulation of diverse deleterious changes in the cells and tissues leading to increased risk of diseases. Oxidative stress is considered as a major risk factor and contributes to age related increase in DNA oxidation and DNA protein cross-links in central nervous system during aging. In the present study, we have evaluated the salubrious role of grape seed extract on accumulation of oxidative DNA damage products such as 8-OHdG and DNA protein cross-links in aged rats. Male albino rats of Wistar strain were divided into four groups: Group I, young control rats; Group II, young rats treated with grape seed extract (100 mg/kg b.wt.) for 30 days; Group III, aged control rats; Group IV, aged rats supplemented with grape seed extract (100 mg/kg b.wt.) for 30 days. Our results, thus, revealed that grape seed extract has inhibiting effect on the accumulation of age-related oxidative DNA damages in spinal cord and in various brain regions such as cerebral cortex, striatum and hippocampus.

Age-related oxidative protein damages in central nervous system of rats: modulatory role of grape seed extract

Oxidative stress has been shown to play a major role in aging and in neurodegenerative disorders. Protein modification is one of the important consequences of oxidative stress. In the present study, we evaluated the role of grape seed extract on memory, reactive oxygen species production, protein carbonyls (PCO), and thiol status in discrete regions of central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I—control young rats, Group II—young rats treated with grape seed extract (100mg/kg BW) for 30 days, Group III—aged control rats and Group IV—aged rats supplemented with grape seed extract (100mg/kg BW) for 30 days. Memory loss was observed in the aged rats. Age associated increase in reactive oxygen species production and protein oxidation was observed in the spinal cord; cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). The levels of total thiol, non-protein thiol, protein thiols were found to be significantly decreased in spinal cord and all the brain regions studied in aged rats when compared to young rats. Supplementation of aged rats with grape seed extract showed increased memory performance and declined reactive oxygen species production, decreased protein carbonyl levels and improved thiol levels. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical induced protein oxidation in aged rats thereby protecting the central nervous system from the reactive oxygen species.

Rejuvenation of antioxidant system in central nervous system of aged rats by grape seed extract

Oxidative stress is considered as a major risk factor that contributes to age-related increase in lipid peroxidation and declined antioxidants in the central nervous system during aging. Grape seed extract, one of the bioflavonoid, is widely used for its medicinal properties. In the present study, we evaluated the role of grape seed extract on lipid peroxidation and antioxidant status in discrete regions of the central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I—control young rats, Group II—young rats treated with grape seed extract (100 mg/kg body weight) for 30 days, Group III—aged control rats and Group IV—aged rats supplemented with grape seed extract (100 mg/kg body weight) for 30 days. Age-associated increase in lipid peroxidation was observed in the spinal cord, cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). Activities of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase and levels of non-enzymic antioxidants like reduced glutathione, Vitamin C and Vitamin E were found to be significantly decreased in all the brain regions studied in aged rats when compared to young rats. However, normalized lipid peroxidation and antioxidant defenses were reported in the grape seed extract-supplemented aged rats. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in the central nervous system of aged rats.

Oxidative stress on mitochondrial antioxidant defense system in the aging process: Role of dl-α-lipoic acid and l-carnitine

Background Oxidative damage is hypothesized to accumulate throughout the lifetime of an organism, eventually giving rise to aging. The mitochondria may be the primary cellular source and target of endogenous ROS as they are produced as a normal byproduct of the electron transport system. Methods Male albino Wistar rats were used in this study. The animals were divided into 6 groups, each group consisting of 6 animals. Groups I, III, and V were young, middle-aged and aged control rats and Groups II, IV, and VI were treated with carnitine (300 mg/kg bw) and dl-α-lipoic acid (150 mg/kg bw), respectively. After the treatment period, the animals were sacrificed and the heart and skeletal muscle were removed for analysis. Result There was a significant reduction in the levels of antioxidants in both middle-aged and aged rats whereas the thiobarbituric acid reactive substances were found to be increased. Co-supplementation of carnitine and lipoic acid improved the antioxidant status and brought down the levels of TBARS. Conclusion Co-supplementation of lipoic acid with carnitine has a beneficial effect in reversing the age-related abnormalities seen in aging. This effect was associated with the decrease in free radical production and rise in antioxidant levels by carnitine and lipoic acid, thereby lowering oxidative stress.

The effects of ageing on brain tissue sialic acid contents following cold trauma.

There is a prominent difference between the responses of young and aged patients to brain injury in the clinical setting, but the exact cause of this condition is not well known. Young (3-4 months) and aged (36-40 months) Wistar albino male rats were used as subjects, and they were divided into four groups: young and aged study groups, and young and aged control groups. In all groups, craniectomies were performed over the left hemispheres, and in the study groups, cold injuries were inflicted. Brain tissue sialic acid contents were determined in all groups. Brain tissue sialic acid content was higher in aged control rats than young control ones, but the difference was not statistically significant. Tissue sialic acid content was significantly increased in young rats after trauma. On the contrary, it was significantly decreased in aged rats after trauma. In young rats, brain tissue sialic acid content was significantly increased 24 hours after cold injury unlike in the aged ones. This may be a finding related to decreased regeneration capability of aged brain.

Paradoxical effects of cortical impact injury on environmentally enriched rats.

Animals housed in an enriched environment develop thicker cortices, with increased numbers of dendrites, synapses, blood vessels, and glial cells. This study examines the responses of adult rats, developmentally reared in an enriched environment, to traumatic brain injury. Rats were placed in an enriched environment for 15 days, starting on postnatal day 21. Following enrichment, they were placed in standard vivarium conditions until adulthood. At 3 months of age, enriched and age-matched control rats received a mild unilateral controlled cortical impact and were allowed to recover for 41 days. During this time, they were examined for motor coordination deficits and for preferences in forelimb use. Results demonstrate that enriched animals had a larger contusion cavity and a greater initial deficit in forelimb use. However, this deficit quickly diminished in comparison to that seen in non-enriched injured rats. The deficit in motor coordination recovered more quickly in enriched rats, 1 week sooner than in controls. These data suggest that the response of enriched animals to brain injury results in more marked neurodegeneration and acute behavioral dysfunction, with a higher capacity for compensation and recovery.

Conjugated equine estrogens reverse the effects of aging on central and peripheral allopregnanolone and beta-endorphin levels in female rats

Objective To compare β-endorphin and allopregnanolone levels and their response to a 2-week oral estrogen treatment with conjugated equine estrogens (CEE) in young ovariectomized (ovx) and in healthy aged female rats. Design Prospective study. Setting Animal laboratory in an academic environment. Animal(s) Twenty-four young ovx and 24 healthy aged female Wistar rats were treated with CEE. Three 8-rat control groups (cycling, ovx, and aged rats) were also included. Intervention(s) Treated rats underwent 14-day oral treatment with three doses of CEE: 0.1 mg/kg/day, 0.5 mg/kg/day, and 2 mg/kg/day. Main outcome measure(s) Cerebral and peripheral β-endorphin and allopregnanolone levels. Result(s) Beta-endorphin levels were lower in aged vs. cycling and ovx control rats. In brain and serum allopregnanolone levels were lower in aged vs. cycling control rats, whereas in the adrenals they were higher in aged vs. cycling animals. In the hypothalamus and anterior pituitary allopregnanolone levels were lower in ovx vs. aged animals. In both ovx and aged animals, CEE treatment reverted the effects of ovariectomy and aging, in a dose-dependent manner. Conclusion(s) Aging is associated with a decrease in cerebral and peripheral β-endorphin and allopregnanolone. In hypoestrogenic rats, CEE treatment restores allopregnanolone and β-endorphin content; this indicates a role for these compounds as neuroendocrine mediators of the effects of estrogens.

THE IMPACT OF MUSCLE UNLOADING ON NEUROMUSCULAR JUNCTION MORPHOLOGY IS AGE DEPENDENT

The effects of unloading on aged and young muscle have been well documented. However, the impact of unloading on the neuromuscular junctions (NMJs) of aged and young adult muscle has yet to be determined. PURPOSE The aim of this investigation was to assess the morphological plasticity of the NMJs of older and younger animals subjected to muscle unloading. METHODS Sixteen young adult (8 mo) and 16 aged (22 mo) male rats were assigned to either hindlimb suspension (HS), or control conditions (N=8/group) for a period of 4 wks. Following euthanization, soleus muscles were sectioned and stained using cytofluorescent procedures to visualize pre-synaptic acetylcholine vesicles and postsynaptic acetylcholine receptors. Images of NMJs were captured with a confocal microscope. Various aspects of pre- and post-synaptic NMJ morphology, including area and perimeter, were quantitated. RESULTS Among young adult rats, unloading failed to elicit significant alterations in either the pre-, or the post-synaptic components of NMJ morphology. In contrast, unloading among the aged rats resulted in significant (P < 0.05) increases in pre- and post-synaptic area (32% and 43%, respectively), and perimeter (15% and 17%). No significant differences in NMJ morphology were detected between young adult and aged control rats, i.e., no significant main effect of aging. CONCLUSION These data indicate that unlike young adult NMJs, the synapses of aged skeletal muscle undergo significant remodeling as a result of prolonged unloading. Importantly, these alterations cannot be ascribed to initial differences among aged and young adult control NMJs. Supported by NIH grant AG 1744C, and the Howard Hughes Medical Institute through a grant to The College of William & Mary.

Role of gastrin in the development of gastric mucosa, ECL cells and A-like cells in newborn and young rats.

Histamine-producing ECL cells and ghrelin-producing A-like cells are endocrine/paracrine cell populations in the acid-producing part of the rat stomach. While the A-like cells operate independently of gastrin, the ECL cells respond to gastrin with mobilization of histamine and chromogranin A (CGA)-derived peptides, such as pancreastatin. Gastrin is often assumed to be the driving force behind the postnatal development of the gastric mucosa in general and the ECL cells in particular. We tested this assumption by examining the oxyntic mucosa (with ECL cells and A-like cells) in developing rats under the influence of YF476, a cholecystokinin-2 (CCK(2)) receptor antagonist. The drug was administered by weekly subcutaneous injections starting at birth. The body weight gain was not affected. Weaning occurred at days 15-22 in both YF476-treated and age-matched control rats. Circulating gastrin was low at birth and reached adult levels 2 weeks after birth. During and after weaning (but not before), YF476 greatly raised the serum gastrin concentration (because of abolished acid feedback inhibition of gastrin release). The weight of the stomach was unaffected by YF476 during the first 2-3 weeks after birth. From 4 to 5 weeks of age, the weight and thickness of the gastric mucosa were lower in YF476-treated rats than in controls. Pancreastatin-immunoreactive cells (i.e. all endocrine cells in the stomach) and ghrelin-immunoreactive cells (A-like cells) were few at birth and increased gradually in number until 6-8 weeks of age (control rats). At first, YF476 did not affect the development of the pancreastatin-immunoreactive cells, but a few weeks after weaning, the cells were fewer in the YF476 rats. The ECL-cell parameters (oxyntic mucosal histamine and pancreastatin concentrations, the histidine decarboxylase (HDC) activity, the HDC mRNA levels and serum pancreastatin concentration) increased slowly until weaning in both YF476-treated and control rats. From then on, there was a further increase in the ECL-cell parameters in control rats but not in YF476 rats. The postnatal development of the ghrelin cells (i.e. the A-like cells) and of the A-like cell parameters (the oxyntic mucosal ghrelin concentration and the serum ghrelin concentrations) was not affected by YF476 at any point. We conclude that gastrin affects neither the oxyntic mucosa nor the endocrine cells before weaning. After weaning, CCK(2) receptor blockade is associated with a somewhat impaired development of the oxyntic mucosa and the ECL cells. While gastrin stimulation is of crucial importance for the onset of acid secretion during weaning and for the activation of ECL-cell histamine formation and secretion, the mucosal and ECL-cell growth at this stage is only partly gastrin-dependent. In contrast, the development of the A-like cells is independent of gastrin at all stages.

Diets Enriched in Foods with High Antioxidant Activity Reverse Age-Induced Decreases in Cerebellar β-Adrenergic Function and Increases in Proinflammatory Cytokines

Antioxidants and diets supplemented with foods high in oxygen radical absorbance capacity (ORAC) reverse age-related decreases in cerebellar β-adrenergic receptor function. We examined whether this effect was related to the antioxidant capacity of the food supplement and whether an antioxidant-rich diet reduced the levels of proinflammatory cytokines in the cerebellum. Aged male Fischer 344 rats were given apple (5 mg dry weight), spirulina (5 mg), or cucumber (5 mg) either in 0.5 ml water by oral gavage or supplied in the rat chow daily for 14 d. Electrophysiologic techniques revealed a significant decrease in β-adrenergic receptor function in aged control rats. Spirulina reversed this effect. Apple (a food with intermediate ORAC) had an intermediate effect on cerebellar β-adrenergic receptor physiology, and cucumber (low ORAC) had no effect, indicating that the reversal of β-adrenergic receptor function decreases might be related to the ORAC dose. The mRNA of the proinflammatory cytokines tumor necrosis factor-α (TNFα) and TNFβ was also examined. RNase protection assays revealed increased levels of these cytokines in the aged cerebellum. Spirulina and apple significantly downregulated this age-related increase in proinflammatory cytokines, whereas cucumber had no effect, suggesting that one mechanism by which these diets work is by modulation of an age-related increase in inflammatory responses. Malondialdehyde (MDA) was measured as a marker of oxidative damage. Apple and spirulina but not cucumber decreased MDA levels in the aged rats. In summary, the improved β-adrenergic receptor function in aged rats induced by diets rich in antioxidants is related to the ORAC dose, and these diets reduce proinflammatory cytokine levels.

Diets enriched in foods with high antioxidant activity reverse age-induced decreases in cerebellar beta-adrenergic function and increases in proinflammatory cytokines.

Antioxidants and diets supplemented with foods high in oxygen radical absorbance capacity (ORAC) reverse age-related decreases in cerebellar beta-adrenergic receptor function. We examined whether this effect was related to the antioxidant capacity of the food supplement and whether an antioxidant-rich diet reduced the levels of proinflammatory cytokines in the cerebellum. Aged male Fischer 344 rats were given apple (5 mg dry weight), spirulina (5 mg), or cucumber (5 mg) either in 0.5 ml water by oral gavage or supplied in the rat chow daily for 14 d. Electrophysiologic techniques revealed a significant decrease in beta-adrenergic receptor function in aged control rats. Spirulina reversed this effect. Apple (a food with intermediate ORAC) had an intermediate effect on cerebellar beta-adrenergic receptor physiology, and cucumber (low ORAC) had no effect, indicating that the reversal of beta-adrenergic receptor function decreases might be related to the ORAC dose. The mRNA of the proinflammatory cytokines tumor necrosis factor-alpha (TNFalpha) and TNFbeta was also examined. RNase protection assays revealed increased levels of these cytokines in the aged cerebellum. Spirulina and apple significantly downregulated this age-related increase in proinflammatory cytokines, whereas cucumber had no effect, suggesting that one mechanism by which these diets work is by modulation of an age-related increase in inflammatory responses. Malondialdehyde (MDA) was measured as a marker of oxidative damage. Apple and spirulina but not cucumber decreased MDA levels in the aged rats. In summary, the improved beta-adrenergic receptor function in aged rats induced by diets rich in antioxidants is related to the ORAC dose, and these diets reduce proinflammatory cytokine levels.

Life-long impairment of hypoxic phrenic responses in rats following 1 month of developmental hyperoxia.

Hypoxic ventilatory and phrenic responses are reduced in adult rats (3-5 months old) exposed to hyperoxia for the first month of life (hyperoxia treated). We previously reported that hypoxic phrenic responses were normal in a small sample of 14- to 15-month-old hyperoxia-treated rats, suggesting slow, spontaneous recovery. Subsequent attempts to identify the mechanism(s) underlying this spontaneous recovery of hypoxic phrenic responses led us to re-evaluate our earlier conclusion. Experiments were conducted in two groups of aged Sprague-Dawley rats (14-15 months old) which were anaesthetized, vagotomized, neuromuscularly blocked and ventilated: (1) a hyperoxia-treated group raised in 60 % O2 for the first 28 postnatal days; and (2) an age-matched control group raised in normoxia. Increases in minute phrenic activity and integrated phrenic nerve amplitude (integral Phr) during isocapnic hypoxia (arterial partial pressures of O2, 60, 50 and 40 +/- 1 mmHg) were greater in aged control (n = 15) than hyperoxia-treated rats (n = 11; P < or = 0.01). Phrenic burst frequency during hypoxia was not different between groups. To examine the central integration of carotid chemoafferent inputs, steady-state relationships between carotid sinus nerve (electrical) stimulation frequency and phrenic nerve activity were compared in aged control (n = 7) and hyperoxia-treated rats (n = 7). Minute phrenic activity, integral Phr and burst frequency were not different between groups at any stimulation frequency between 0.5 and 20 Hz. Carotid body chemoreceptor function was examined by recording whole carotid sinus nerve responses to cessation of ventilation or injection of cyanide in aged control and hyperoxia-treated rats. Electrical activity of the carotid sinus nerve did not change in five out of five hyperoxia-treated rats in response to stimuli that evoked robust increases in carotid sinus nerve activity in five out of five control rats. Estimates of carotid body volume were lower in aged hyperoxia-treated rats (4.4 (+/- 0.2) x 10(6) microm3) compared to controls (17.4 (+/- 1.6) x 10(6) microm3; P <0.01). We conclude that exposure to hyperoxia for the first month of life causes life-long impairment of carotid chemoreceptor function and, consequently, blunted phrenic responses to hypoxia.

Age-associated loss of bone marrow hematopoietic cells is reversed by GH and accompanies thymic reconstitution.

Deterioration of the thymus gland during aging is accompanied by a reduction in plasma GH. Here we report gross and microscopic results from 24-month-old Wistar-Furth rats treated with rat GH derived from syngeneic GH3 cells or with recombinant human GH. Histological evaluation of aged rats treated with either rat or human GH displayed clear morphologic evidence of thymic regeneration, reconstitution of hematopoietic cells in the bone marrow, and multiorgan extramedullary hematopoiesis. Quantitative evaluation of formalin-fixed, hematoxylin and eosin-stained sections of bone marrow from aged rats revealed at least a 50% reduction in the number hematopoietic bone marrow cells, compared with that of young 3-month-old rats. This age-associated decline in bone marrow leukocytes, as well as the increase in bone marrow adipocytes, was significantly reversed by in vivo treatment with GH. Restoration of bone marrow cellularity was caused primarily by erythrocytic and granulocytic cells, but all cell lineages were represented and their proportions were similar to those in aged control rats. On a per-cell basis, GH treatment in vivo significantly increased the number of in vitro myeloid colony forming units in both bone marrow and spleen. Morphological evidence of enhanced extramedullary hematopoiesis was observed in the spleen, liver, and adrenal glands from animals treated with GH. These results confirm that GH prevents thymic aging. Furthermore, these data significantly extend earlier findings by establishing that GH dramatically promotes reconstitution of another primary hematopoietic tissue by reversing the accumulation of bone marrow adipocytes and by restoring the number of bone marrow myeloid cells of both the erythrocytic and granulocytic lineages.

In Vivo Peritoneal Chamber: Linking Structure and Transport Function

The present study aimed to develop an animal model of chronic peritoneal exposure that directly links transport with the tissue involved. Daily, rats were intraperitoneally infused through subcutaneous ports with 20 mL of these solutions: isotonic Krebs (K), K + 2.5% mannitol (M), K + 2.5% N-acetylglucosamine (NAG). Controls included catheter-only (CC) and age-control rats (AC). After 2 months, each rat was anesthetized and a plastic chamber was affixed to the abdominal wall serosa to isolate a portion of the peritoneum for transport studies. In the first 90 minutes, a hypertonic solution (approximately 500 mosm/kg) containing 14C-mannitol was placed in chamber. The volume and 14C concentration were measured to determine the rate of osmotic flux (flow/Area(chamber)) into the chamber and the flux of mannitol from the chamber to the tissue. At 90 minutes, fluorescein isothiocyanate conjugate (FITC)-albumin was given intravenously. The rate of appearance of that substance in the chamber was measured over a period of 180 minutes and divided by Area(chamber) to determine the average flux. After the rat was humanely killed, the tissue under the chamber was collected for analysis of its hyaluronan concentration ([HA]). All data are given as mean +/- standard error: [table: see text]. In the present pilot study, no significant correlations were observed, but the number of animals in each group was small (n = 3-4). Nevertheless, the results demonstrate the ability of the chamber technique to determine transperitoneal transport of water, small solutes, and protein, and to link those values directly to the structure of the tissue lying below the chamber. Thus, chronic treatment can be directly correlated with peritoneal structure and transport function.

Perinatal asphyxia results in changes in presynaptic bouton number in striatum and cerebral cortex — a stereological and behavioral analysis

Deficits in cognitive function have been related to quantitative changes in synaptic population, particularly in the cerebral cortex. Here, we used an established model of perinatal asphyxia that induces morphological changes, i.e. neuron loss in the cerebral cortex and striatum, as well as behavioural deficits. We hypothesized that perinatal asphyxia may lead to a neurodegenerative process resulting in cognitive impairment and altered presynaptic bouton numbers in adult rats. We studied cognitive performance at 18 months and presynaptic bouton numbers at 22 months following perinatal asphyxia. Data of the spatial Morris water escape task did not reveal clear memory or learning deficits in aged asphyctic rats compared to aged control rats. However, a memory impairment in aged rats versus young rats was observed, which was more pronounced in asphyctic rats. We found an increase in presynaptic bouton density in the parietal cortex, whereas no changes were found in striatum and frontal cortex in asphyctic rats. An increase of striatal volume was observed in asphyctic rats, leading to an increase in presynaptic bouton numbers in this area. These findings stress the issue that volume measurements have to be taken into account when determining presynaptic bouton density. Furthermore, perinatal asphyxia led to region-specific changes in presynaptic bouton numbers and it worsened the age-related cognitive impairment. These results suggest that perinatal asphyxia induced neuronal loss, which is compensated for by an increase in presynaptic bouton numbers.

The effects of a specific α 2-adrenoceptor antagonist, atipamezole, on cognitive performance and brain neurochemistry in aged Fisher 344 rats

The present experiments investigated the effects of a specific and potent α 2-adrenoceptor antagonist, atipamezole, on cognitive performance and neurochemistry in aged rats. Aged control Fisher 344 rats, which had lower activities of choline acetyltransferase in the frontal cortex, were impaired in the acquisition of the linear arm maze task both in terms of repetition errors and their behavioural activity (the speed of arm visits), and they needed longer time to complete this task as compared to adult control rats. Atipamezole treatment (0.3 mg/kg) facilitated the acquisition of this task in the aged rats as they committed fewer errors and completed the task more quickly than saline-treated aged control rats. A separate experiment indicated that atipamezole enhanced the turnover of noradrenaline both in the adult and aged rats, but this effect was more pronounced in the aged rats. Furthermore, atipamezole enhanced significantly the turnover of serotonin and dopamine only in the aged rats when analysed in the whole brain samples. As α 2-adrenoceptor antagonists are known to alleviate akinesia in the experimental models of Parkinson's disease, the present results could be especially relevant for the development of palliative treatment for demented Parkinsonian patients.